25-year savings projection for Illinois
This projection starts from Illinois's assumed $0.16/kWh electricity rate and 1,270 kWh/kW of annual production, then grows savings by 3% a year as electricity prices rise and reduces output by 0.5% a year as panels degrade.
| Year | Annual savings | Cumulative savings | vs. $24,000 cost |
|---|---|---|---|
| Year 1 | $1,339 | $1,339 | −$22,661 |
| Year 5 | $1,478 | $7,039 | −$16,961 |
| Year 10 | $1,671 | $14,997 | −$9,003 |
| Year 15 | $1,889 | $23,994 | −$6 |
| Year 20 | $2,135 | $34,165 | +$10,165 |
| Year 25 | $2,414 | $45,665 | +$21,665 |
A simple, undiscounted projection — it does not apply a discount rate, financing interest, inverter replacement (commonly needed once in 25 years), maintenance, or any change in home value. Treat it as a shape, not a forecast. See methodology.
Why savings look like this in Illinois
Illinois Shines incentive payments materially improve economics that sunshine alone would not support.
The single biggest variable is what your utility pays for exported power. Illinois ended full retail net metering for new customers in 2025; exports are now credited at the supply portion of the rate, with a distributed-generation rebate available in ComEd and Ameren territory to offset the change.
What would change this number
- Your actual rate. This uses a $0.16/kWh Illinois average. If you pay more, savings scale up roughly proportionally.
- Self-consumption. We assume 68% of output is used on site at retail value and the rest exported at 45% of retail. Households home during the day, or with a battery, do better.
- Electricity price growth. At 3% a year, savings nearly double by year 25. Slower growth meaningfully reduces lifetime return.
- Incentives. Illinois's main program — illinois shines (adjustable block program) — reduces net cost and shortens break-even. See Illinois incentives →
- Financing. A cash purchase earns the return above. A loan shifts it — interest can consume a large share of lifetime savings.
Frequently asked questions
How much can you save with solar panels in Illinois?
An 8 kW system in Illinois could save roughly $1,339 in the first year — about $112 a month — and around $45,665 across 25 years, assuming electricity prices rise 3% a year and panel output declines 0.5% a year. Against a midpoint installed cost of $24,000, that is a net gain of about $21,665.
What is the ROI on solar panels in Illinois?
On these assumptions, roughly 90% over a 25-year system life — $21,665 of net savings on a $24,000 system. That is a simple, undiscounted return: it ignores financing interest, the time value of money, and any effect on home resale value. A cash purchase and a loan produce very different numbers.
How long does it take for solar to pay for itself in Illinois?
Around year 16, when cumulative savings first exceed the $24,000 installed cost. A simple payback that ignores rising electricity prices gives a wider range of 16–20 years.
Do solar savings in Illinois include the federal tax credit?
No. The 30% federal residential clean energy credit (Section 25D) ended for systems installed after December 31, 2025, so none of these figures include it. Any savings projection you see elsewhere that still applies 30% to a 2026 purchase is overstating the return.
What most affects solar savings in Illinois?
Three things, in order: your utility's export compensation (Illinois ended full retail net metering for new customers in 2025; exports are now credited at the supply portion of the rate, with a distributed-generation rebate available in ComEd and Ameren territory to offset the change.), how much of the output your household consumes on site rather than exporting, and your actual electricity rate versus the 0.16/kWh state assumption used here. Illinois Shines (Adjustable Block Program) can improve the result further.
Where these numbers come from
State assumptions are informed by public data and reviewed periodically (September 2026):